Brazing preforms are pre-shaped objects of brazing material that are placed in an assembly prior to the heating cycle of a manufacturing process, and which melt in the heating cycle for the desired brazing. For example, in the manufacture of torque converters, ring shaped brazing preforms typically made of copper wire are used to attach turbine blades to the turbine drum in the manufacture of the torque converter drums. That is, the blades are positioned as desired, a brazing ring is positioned around the blades, and the drum is heated to melt the copper to braze the blades to the drum body in the desired positions. Typically, such rings have a diameter of from about 7 to about 12 inches, depending on the size of the torque converter.
The use of brazing preforms, such as copper rings, is advantageous to reduce the need for hand working in the manufacturing process and to more accurately control the amount of brazing material used and its distribution. The use of preforms is also advantageous in the automation of brazing processes. However, the manufacture of brazing preforms, particularly relatively large diameter rings made of relatively small diameter wire, typically involves handwork in joining the ends of the wire to make the ring, such as by crimping or welding. Conventional processes process wire to form a ring having planar ends from a straight cut or shear made to the wire. These planar ends are then aligned and held adjacent one another for welding or crimping. Attempts to automate this process results in a significant number of poor welds or unaligned ends which are unsuitable for use as brazing rings, resulting in substantial waste in the manufacture of the rings. Alternatively, preforms in the form of incomplete rings, e.g., rings with the ends unjoined, are used. The need for handwork to make complete rings is not cost effective and the use of incomplete rings is undesirable to the manufacturing process.
The present disclosure advantageously provides methods and apparatus for the automated manufacture of brazing preforms and, in particular, large diameter complete rings made of small diameter wire.